software package names that contain a suffix denote the environment in which the package was compiled (built). This provides some indication of whether or not a certain package is compatible with one's operating system, but one will not know of compatibility for sure unless the package is actually installed

since the installation of any software package involves occupying partition space, the installation will fail if there is not sufficient, free space on the target installation partition
sometimes installing PET and TXZ packages to frugal Puppy installations requires the amount of free space inside the personal storage file to be at least 3 times the size of the package

to reverse the process, i.e. to un-install PET software packages, go to the un-installing page.

Installing PET packages within frugal Puppy installations

the software installation is only retained (or permanent) when it is installed after the creation of a personal storage save file. The software may be installed before the existence of a save file but the installation will be lost when shutting down or re-booting. A save file is created during the procedure of re-booting or shutting down for the very first time following a new, frugal Puppy installation.